Conventionally, an X-ray diagnostic apparatus has been used for endovascular intervention treatment, for example, using an iodine-based contrast material. In the endovascular intervention treatment, the concentration of the contrast material in a subject may be estimated from an X-ray image obtained by the X-ray diagnostic apparatus. For example, during coronary artery intervention treatment, it is known that the evaluation of perfusion of contrast material into the tissues improves prognosis of patients with ischemic heart disease. Hence, methods for measuring perfusion in a two-dimensional angiographic image have been developed.
In the X-ray diagnostic apparatus, a luminance value (e.g. Signal Intensity) and the concentration of the contrast material in the two-dimensional image are not in a proportional relation, due to scatter, beam hardening, and the like. Thus, to accurately measure perfusion in the two-dimensional angiographic image, the luminance value and the concentration of the contrast material need to be corrected to be in a proportional relation. For example, known correction methods include a method of performing a calibration in advance, a correction method using a phantom, and the like, while the contrast image is obtained. However, in the conventional technology described above, the correction takes time because a complicated calibration is required in advance or a phantom needs to be prepared. Further, it is difficult to perform the correction processing on the contrast image that is already obtained.